1. Introduction
Our main aim was to describe reproductive health with respect to prevalence of major structural congenital anomalies (BD), late miscarriages (M) and still (SB) and premature (P) births in delivery at Al Shifa Hospital, the major maternity hospital of Gaza [
1,
2], and to assess the utility of the comprehensive protocol for registration utilized, inclusive of environmental questions related to exposure to war events. The resulting data will be the baseline for a continuing implementation of the registry, as the primary mean to investigate the quality of the reproductive health and to monitor changes in time in the general health of the population [
3].
The collection of the data on prevalence of birth defects was done according to the local specificities and with modalities that allow also interpretation of changes over time and comparison with other registers from around the world.
BD incidence reflects allelic frequency of genes in the population and varies with its intermarriage rate, but is also susceptible to environmental changes [
4,
5] and has been linked to various sources of pollution, nourishment, mother health, infectious diseases and acute environmental changes of various nature, including use of modern metal augmented weaponry that have teratogen and/or mutagen effects [
6,
7,
8,
9]. Information on the health of siblings of parents and their kin contributes to reinforce, or undermines, the relevance of direct and deterministic genetic contribution for the specific BD in a family. Information on environmental events provides clues of their potential relevance [
10]. Within each class of defect, there is phenotypic variation and some phenotypes are associated with known genetic mutation(s) while for others, the majority still, there is no genetic determinant identified. The change in gene’s functionality can be consequence of mutation or be an epigenetic change or a resultant of both. In many cases maternal environment (including genetic background and external environmental effectors) is involved in the determination of the expression of the phenotype of BD [
5,
8,
9]. In particular, for some of most frequently found BD, is known that the molecular requirements for neural tube closure are complex and implicate a variety of genes, pathways and cellular functions and congenital neural tube defects (NTD) have multifactorial etiology [
11]. Congenital polycystic kidney disease (PKD) is usually associated to homozygosis for mutations in the PKHD1 gene, with variable penetrance [
12]. High prevalence of PKD is recorded in Arab countries, favored by prevalent high rates of intermarriage [
13]. For about 30% of CHD and Tetralogy of Fallot (TOF) there is association with wide genomic rearrangements, and cohort studies have detected genetic mutations in single genes putatively involved in CHD, with very low frequency [
14]. Expression of the CHD is susceptible to environmental effectors. Inheritance of cleft lip and palate in mice is due to combinations of genetic and not genetic factors [
15]. Synpolydactyly is linked to mutations in the gene Hoxd13, but manifestation of the phenotype is dependent upon environmental factors [
16].
Presence of teratogen elements in the post-war environment is expected in Gaza after Operation Cast Lead, because of the kind of metals detected in the weapon systems used [
17,
18]. These have low mutagen but high teratogen and carcinogen potentials, cannot be eliminated from the environment and are capable to act as metalloestrogens affecting multiple cellular pathways during embryo and fetal development [
19,
20,
21]. None of the pregnancies here registered occurred during the major war events when the WP and bombs were used (
i.e., in the Cast Lead operation). Metal load in living organisms is cumulative, and its effects, if any, show over time. We here investigated if there are long term effects on reproductive health that can be associated to cumulative, chronic exposures due to persistence in the environment of not removed toxicants, like the above mentioned endocrine disruptors and metals derived from weapons.
The traditional hyphotesis behind prevalence data surveillance is that detection of a particularly high prevalence of BD in one particular population, or a sudden increase in prevalence over time, points to the existence of some novel environmental cause [
22,
23]. From war theaters where similar weapons were used, the time for teratogen effects to manifest themselves may be on the order of 2–4 years [
6]. These circumstances, in lack of previous record of births and data bank of BD, make relevant to have begun now the recording the prevalence of BD and the state of reproductive health in Gaza.
Our protocol was devised in order to collect demographic and health data, and kin information on the couples with present reproductive problems (BD, M. SB and P) and those with previous events of BD (PBD). For all these, and for normal newborn, parent’s environmental exposure to White Phosphorus (WP), and for BD children parent’s also to bombing, were registered. The questions about environmental exposure were chosen, as occurs in each country, to include also information about the specific circumstances of the country, including environmental factors induced by military attacks.
3. Experimental Section
Our study was wholly conducted in Al Shifa Hospital, in Gaza City, covering 44.4% of deliveries in governmental hospitals in the Gaza strip [
1], with 17,997 births in 2010 [
2] and about 20% of all births of the Strip. A team of trainee doctors covered 18 h/24 and 6/7days for five months and registered 4,027 deliveries and collected the written assent of to the treatment of their data for research report. This is a procedure approved by the local Ministry of Health, the structure to which the Al Shifa Hospital belongs for studies where no reference is done to personal data of patients and these cannot be identified. In most cases both parents signed the form, in some cases the father was absent and only the mother signed also on his behalf. Some individuals accepted only verbally, for mothers this happened usually because stressed by the delivery (all data had to be collected immediately after child birth, due to the rapid dismissal from the hospital after delivery for lack of space), or this was because not everybody was familiar with writing and asked the doctor to proceed registering their verbal consent, which was registered in the original files. A summary of the information given and the request of permission are included in the questionnaire, shown in its whole in
Table 1 (in full in
S-Table I). The first section of the questionnaire was filled for all deliveries and a second one was reserved for deliveries of a BD child, premature (P) and still births (SB) and in case of late miscarriages (M) and in the case that during the interview emerged that the couple with a normal newborn had previously a child with birth defect (PBD). Termination of pregnancies is not practiced in Gaza and miscarriages of less than 16 weeks are not registered, as occurs also in other national registries of countries where abortions are not allowed by the law or beliefs.
Clinical diagnosis were from the doctors in charge of the delivery room, confirmed, if appropriate, by the doctors in the Intensive care unit (equipped with pulse oxy-meters and portable ultrasound machine). We have registered the major structural BD according to the Eurocat/ICD10 nomenclature [
25,
26] grouped according to the primary defect [
27,
28]. This choice is in line with most registers available. Multiple malformations, are classified independently only if there is no obvious way to identify the primary defect. We refer for comparative purposes to the information provided in the 2009 report from ICHBDSR [
28] based on the same criteria we used, and avoid reference to the data from countries where there is heterogeneity in the modalities of collection of data. M are deliveries after 16 weeks and before 28 weeks. These were spontaneous emergency cases and not diagnosis or exams where done on the fetus. P are children born below 1.5 kg, and if there was a birth defect the child was registered by us also among BD. SB are born dead after 28 weeks.
Statistics. Prevalence data are expressed as percentage; incidence rate for normal children, BD and premature births are expressed as number per 1,000 registered live births (3,919) while incidence rate for late miscarriages and stillborn is calculating using as denominator total deliveries (4,027). Comparisons between each subgroup and normal were performed using Fisher’s test. Confidence intervals are given and a P value < 0.05 was considered significant.
4. Conclusions
The prevalence of BD in Gaza strip is 14/1,000. Within the limits due to differences in diagnostic levels, dimension of samples and methodologies, this is comparable to that of less industrialized countries and lower that that reported for more industrialized US (30/1,000) and Europe (23/1,000) (
s-Table VII). Information is not available to compare incidence of M; that of SB is comparable with other countries and premature born in Gaza are less frequent than reported in the USA (the highest in the developed world).
Ours was a pilot study to first assess prevalence of BD. Our approach using a pre-specified questionnaire seems adequate, with a good feasibility as testified by the short time to train participating doctors and the ease in completing the questionnaires by the mothers. The main limitation is related to the present circumstances in Gaza that allow diagnosing BD at birth almost exclusively on clinical basis. As a consequence, the prevalence of total BD we report here is underestimated. Underestimate is suggested strongly for CHD which emerges as the most frequent BD in the records of 0–2 year old patients of pediatric hospitals [
29].
There are noticeable differences from other countries in prevalence in Gaza for two kinds of BD: considerably higher prevalence of congenital PKD, usually due to homozygosis for mutations in a single gene [
12] and lower prevalence of genital defects. For these last in Al Shifa no cases of undescended testis were registered, while this accounts for the highest numbers of the genital defects in many other countries. The high prevalence of PKD, among renal defects, reveals a polymorphism in the PKHD1 gene, common to other Arab counties [
13].
Distribution of most of other major BD is not significantly different in our register that in other countries (
Supplementary Table VII, compiled from the 2009 report by ICHBDSR) [
28]. Although intermarriage in Gaza occurs with high frequency, marriage between first cousins is not associated to occurrence of BD or M. Provisionally, we could not establish any specific association with first cousin marriage, as one would expect for a recessive genetic defect, even for PKD, a fact that requires further study. It will be possible to evaluate better the relevance of intermarriage with reference of each specific kind of BD once a larger size of the sample of registered BD will be obtained by establishing widely the at birth registration procedure. Increase of sample number will also expose the level of polymorphism in the population for frequent recessive alleles, or will be supportive of the relevance of local environmental factors.
We also report recurrence of BD within a couple, and that in the numerous siblings of the parents which is not significantly higher than in the general population, and the increase in frequency of M in couples with a BD child or with history of M. Nonetheless, even for the BD recurring in a couple, only in 50% of cases these are of the same primitive embryonic origin. Thus, seemingly, these recurrences of BD in the couple are often due to disjoint events of mutation or of epigenetic changes in a favorable genetic background or to variable phenotypic expression. At this stage we cannot distinguish among these possibilities. While the recurrence of a PKD could be attributed to parents heterozygosis, the fact that NTD, known as multifactorial and environmentally influenced, recur in the couple with similar or higher frequency suggest that high pre-existing genetic polymorphisms is only one of the mechanisms at the basis of BD reiteration.
The increase in M in the couples with BD agrees with the concept that often M are spontaneous abortion caused by BD, although we cannot prove this causality in lack of diagnosis on the aborted fetuses.
Overall, collaterals of couples with BD have no higher rate of BD than the general population and not always recurrence of the same type of BD, and only in some cases there is ground to assume a familiar genetic origin.
Both limited instances of familiar expression and modalities of recurrence of different BDs are compatible with a role for environmental events in the promotion of the incidence of (some) BD.
We show a strong correlation of BD newborns and parent’s exposure to attacks with WP, and a high frequence of exposure in these couples to bombing, and/or consequent rubble cleaning, and we retraced data showing the accuracy of the recollection of exposures. It emerges the strong suggestion that exposure to war-derived elements enhances BD occurrence at a successive time. Before being conclusive on the specific elements in these weaponry that may cause such effects, analysis of contamination by war-related toxicants needs to be done.
There is provisional indication that the incidence of BD, M and SB may be occurring preferentially in Gaza city, while PBD in the North. To confirm these differences in BD’s distribution, we need to collect the data from more deliveries with BD and we need to extend implementation of our questionnaire to maternities covering all the areas of the Gaza strip.
We present for the first time for Gaza strip, limited to the major maternity hospital, prevalence of major birth defects, late miscarriages, prematurely and still born children, the rates of survival in the short term, the sex ratio and intermarriage frequency in the population.
We present the validity of a protocol for data collection which allows to understand the modalities and to investigate the nature of events that produce the BD.
Through the collection of regionally relevant environmental exposures, we established correlation of negative reproductive events with confirmed exposure to war, a fact relevant for the etiology of the birth diseases in Gaza.
Since no previous prevalence data are available for this population or this Hospital, we do not have the possibility to compare the present data of incidence with the situation previous to the war of the winter 2008–2009, and we do not know if the prevalence is higher now than previous to war.
The correlation between children with defect at births and war exposure of their parents points to this possibility and rises serious concerns, which should be further investigated. Other potential teratogen elements in the environment are now also under study.
In conclusion, we show that in a majority of cases the birth defects occur as novel events without collateral family history and recur in the same couple and not in their collaterals, with different or same malformation, regardless of the consanguineity of parents and in strong correlation with exposure to White phosphorus and other bombing events.